Method for the manufacture of gas



Filed July 28, 1937 lNVENTOR 0? C'- ,%a 46/: BY

ATTORNEYS Patent ed 0 i. 24, 1939 PATENT OFFICE METHOD roa 'rns MANUFACTURE or GAS Claude 0. Van Nuys, (i'antord, N. J., asslgnor to Air Reduction Company, Incorporated. New, York, N. Y., a. corporation of New York Application July 28,1937, Serial No. 156,147

6 Claims. (01. 48-197) This invention relates to a method and apparatus for the production from solid or liquid carbonaceous fuels of a gas of high calorific value suitable for heating, lighting and other purposes.

Two methods of producing gas from solid and liquid carbonaceous fuels have been in general use heretofore. One involves the destructive distillation of coal in retorts. The other is the socalled water gas method.

The destructive distillation of coal in retorts produces gas of excellent quality, but the operation is relatively expensive and the method has been superseded generally except in isolated local gas plants. The cost of the gas thus obtained prevents general use of the method for ordinary commercial purposes.

The water gas method is widely used. It is an intermittent operation in which a body of coke is ignited and blown with a current of air until the bed is highly incandescent. In the second stage, the air is shut off and the incandescent fuel bed is blown with steam ascending or descending through the bed. During the initial or blow period, the effluent gas leaving the top of' the producer has a low calorific value and it is employed generally in superheating the steam which is used in the second or make" period.

The action of the steam upon the incandescent coke is to convert the carbon of the coke into carbon monoxide according to the equation The product leaving the top of the producer during the make period is a mixture of carbon monoxide and hydrogen and is known in industry as blue water gas. The calorific value of this gas does not exceed about 250 B. t. u. per cubic foot.

To secure a gas of high calorific value suitable, for example, for use as an illuminating gas, it is necessary to have a calorific value of approximately 550 B. t. u. per cubic foot or better. In the water gas method, the additional thermal units are supplied by the destructive distillation of petroleum oil which is added to the blue water gas". The reaction is known as "cracking and a large part of the cost of the finished product is due to the-enrichment ofthe blue water gas.

It is the object of the present invention to provide a method and apparatus whereby a gaseous product of high calorific value equal to or exceeding 550 B. t. 11. per cubic foot can be produced continuously from fuel, steam and oxygen reacting contemporaneously and under conditions which may be regulated readily to afford a product of the desired characteristics.

Other objects and advantages of the invention will be apparent as it is better understood by reference to the following specification and the accompanying drawing, in which Fig. l is a diagrammatic illustration of an apparatus in which the desired reactions may be conducted;

Fig. '2 is a section on the line 2--2 of Fig. l; and

Fig. 3 is a detail in section illustrating a nozzle supplied with oxygen and pulverized fuel.

It will be observed that the apparatus as delineated in the drawing is merely illustrative of the essential features and that the method may be carried out in any suitable apparatus wherein the principles of the invention can be utilized.

Carbon dioxide is an undesirable constituent of the gaseous product since it serves as a diluent and reduces the calorific value of the product. It is difficult to remove carbon dioxide from the gas and consequently formation of carbon dioxide is to be avoided. This is accomplished by maintaining the initial reaction of the fuel with oxygen at the highest attainable temperature, at which temperature carbon dioxide is not produced.

I have discovered that the desired type of combustion can be maintained by directing fuel and oxygen in opposite directions in the form of jets which impinge. A considerable excess of fuel over that which will react with the oxygen is employed, and the jet of oxygen is introduced at high velocity 50 that it penetrates the jet of fuel. The initial reaction occurs at or adjacent the point where the two jets meet and is evidenced by a ball of fiame which attains a very high temperature. bon of the fuel is partially consumed and converted into carbon monoxide.

To complete the reaction, steam is introduced intermediate the fuel and the oxygen jets. The steam is deflected so that it is caused to mingle with the gases at relatively high temperature resulting from the initial combustion, and with the highly heated fuel particles consisting of unconsumed carbon. At the temperature resulting from the initial combustion, the steam reacts with the carbon of the fuel in accordance with the reaction with the resulting production of carbon monoxide and hydrogen. These products, mingled with the carbon monoxide produced by the initial In this combustion, the carreaction, escape from the reaction zone. Some of the heat maybe utilized in initially heating the fuel which is introduced. The gas then escapes and may be delivered to a dust catcher or any other suitable device adapted for the removal of any solid particles. It may be delivered then to a gas holder or to burners in which it is consumed for the purpose of utilizing its heating value.

Oil is an ideal fuel for conversion into gas in the manner described, but pulverized coal may be used as a part of the fuel by introducing it with oxygen. This is accomplished preferably by employing a conveyor, e. g. the worm or helical type, disposed within the pipe which supplies the jet of oxygen, so that the pulverized carbonaceous fuel is injected with the oxygen jet into the reaction zone, where it meets the remainder of the fuel in a state of liquid oil.

The method of the present invention is characterized by the following features:

1. All three of the components concerned in the reactions, to wit, fuel, steam and oxygen, are fed contemporaneously and in such a manner that they all act co-locally in a reaction zone wherein all of the reactions occur to produce the final product.

2. All three components are introduced in the form of a plurality of jets through nozzles of suitable diameter. The nozzles employed to introduce any single component are, in general, of equal diameter, and of different diameter from the nozzles introducing any other component.

3. The nozzles by means of which liquid fuels are introduced are oppositely directed to and larger than the nozzles which introduce the oxygen. The axis of any, single oxygen nozzle coincides with the axis of an opposed fuel nozzle sothat the oxygen jet may penetrate the jet of fuel,

thereby assuring adequate mixture and the localizing of the initial combustion and of the highest temperature.

4. When a part of the fuel is pulverized coal, it is introduced into the furnace through a suitable feed at high velocity by means of the oxygen jet, which travels in the same direction with it and communicates to it most of the velocity of the oxygen. This powdered coal and oxygen take the form of a more or less elongated flaming jet, which collides with the oil jet directly opposite and produces an intensely heated ball flame, similar to the effect produced when the fuel is all oil.

5. The steam nozzles are scattered among the oxygen nozzles in a regular manner and may or may not equal in number the oxygen nozzles, but are sufficient in capacity to supply steam in ample quantity to complete the gas formation.

By variation of the quantity of oxygen admitted relative to the quantity of fuel admitted, by variation of the velocity at which the three fluids enter, and by regulation of the quantity of steam added to the quantity of fuel admitted, it is possible to vary the calorific value of the product from about 300 B. t. u. per cubic foot to 1300 B. t. u. per cubic foot. The resulting product consists essentially of carbon monoxide and hydrogen with proportions of methane, ethylene, ethane and propylene and possibly other hydrocarbons.

Referring to the drawing, 5 indicates a combustion chamber which may be constructed of any suitable material, being preferably lined with a refractory adapted to withstand temperatures up to about 1000 F. The chamber may be circular in cross-section, as indicated in Fig. 2, but this is in no way essential, and the chamber may have any desired form. Projecting through the wall i at one end of the chamber are a plurality of nozzles I connected to a source of oxygen under pressure. These nozzles may be constructed of any suitable material adapted to withstand the temperature developed. The highest temperatures are isolated from the nozzles, since they occur only at the point of impingement of the oxygen with the fuel. Consequently no difficulty has been experienced in maintaining the nozzles for oxygen, fuel or steam. A wall 8 at the opposite end-of the chamber 5 supports a plurality of fuel nozzles 8 so placed as to be directly opposed to the nozzles I. Pipes l0 connected to the nozzles 8 extend through a chamber It and are connected to a source of liquid fuel such as petroleum oil. The oil is fed under suitable pressure so that the jet of oil is projected axially toward the opposed oxygen jet. The latter is directed under higher velocity so that it meets and penetrates the fuel jet, with the resulting initial combustion and the production of the high temperature flame.

Between the oxygen nozzles I are a plurality of steam nozzles I! which are connected to and adapted to be supplied from a source of steam under suitable pressure. The steam jets are introduced between the regions of highest temperature and impinge upon deflectors l3 supported on the wall 8. -These deflectors may be of any suitable material, preferably ceramic in nature; although they are maintained at a relatively low temperature by the steam which impinges upon them. The deflectors cause the steam to mingle with the gaseous products of the initial combustion and with fuel particles brought to high temperature by that combustion, so that reaction of the steam with the highly heated fuel particles is conducted simultaneously with the initial combustion of the carbon of the fuel with oxygen. The result is a gaseous mixture of the character hereinbefore described. It escapes through a plurality of ports I in the wall 8 into the chamber II where it surrounds the pipes l0 and thus gives up a part of its heat to the incoming fuel. The gas is then withdrawn through an outlet l5 and conveyed to the dust catcher (not shown).

In Fig. 3 of the drawing, I have illustrated one of the pipes 1, in which a pipe I6 is internally arranged with'a worm feed device I1, adapted to be supplied in a suitable manner with pulverized fuel. The worm feed device advances the pulverized fuel and feeds it to the oxygen, which flows through the surrounding space, forming a flaming jet which collides with the oppositely directed oil jet, with the result that the oxygen is consumed and the excess fuel is heated to a high temperature, which subsequently reacts with the steam introduced through nozzles l2.

From the foregoing, it will be observed that the procedure invloves the essential feature of direct impingement of the oxygen upon the fuel jet, whereby the initial combustion is maintained in a localized zone represented by the ball of flame which is characteristic of this type of combustion. At the same time, the excess fuel reacts with the steam introduced, as explained above, and is distributed so that practically all of the steam is consumed to form carbon monoxide and hydrogen, while the unconsumed residue of oil is crackedtin the cooler parts of the furnace, and the result is a gas of a higher caloriflc power than has previously been produced in a single operation by other methods. The temperature attained by the initial combustion prevents the formation of any carbon dioxide, and the steam reaction does not produce carbon dioxide in any substantial quantity, so that the immediate result is a gas of the desired calorific value. The operation is continuous, that is to say, there are no alternating periods of operation as in the ordinary water gas method. The gaseous product, moreover, requires no secondary carburetion, which is an essential element of the water gas method when utilized to produce a gas of high calorific value.

An important feature of the invention is that combustion of the available oxygen occurs in the absence of steam, which does not penetrate the high temperature zones where the fuel and oxygen impinge. The only component in the high temperature zones other than oxygen is the fuel supplied, which, as hereinbefore indicated, includes an excess over that which may be burned by the amount of oxygen supplied.

Various changes may be made in the form and structure of the apparatus as well as in the de- 1. The method of producing gas of high-calorific value from finely divided fuels which comprises projecting the fuel and oxygen in opposed co-axial jets, the fuel being in excess of the amount which will react with the oxygen supplied, maintaining combustion at the zone where the opposing jets collide and exclude steams and simultaneously introducing steam in the region surrounding the jets for reaction with highly heated surplus fuel which is not burned with oxygen.

2. The method of producing gas of high calorific value from finely divided fuels which comprises projecting the fuel and oxygen in opposed co-axial jets, the fuel being in excess of the amount which will react with the oxygen supplied, maintaining combustion at the zone where the opposing jets collide and exclude steam, simultaneously introducing steam in the region surrounding the jets for reaction with highly heated surplus fuel which is not burned with oxygen, and preheating the fuel by heat exchange with the gas produced therefrom.

3. The method of producing gas of high calorific value from liquid fuel only which comprises projecting the fuel and oxygen in opposed coaxial jets, the fuel being in excess of the amount which will react with the oxygen supplied, maintaining combustion at the zone where the passing jets collide and exclude steam, and simultaneously introducing steam into the region surrounding the jets for reaction with the highly heated surplus 'fuel which is not burned with oxygen.

4. The method of producing gas of high calorific value from finely divided fuels which comprises maintaining a high temperature zone of combustion uncontaminated by steam by axially impinging streams of fuel and oxygen, the fuel being in excess of the amount which will react with the oxygen, and in the space surrounding the combustion zone simultaneously reacting steam with the highly heated surplus fuel which is not burned with oxygen.

5. The method of producing gas of high calorific value from finely divided fuels which comprises maintaining a high temperature zone of combustion uncontaminated by steam by axially impinging streams of fuel and oxygen, the ratio of the masses of fuel and oxygen fed being in excess of that required for the oxidation which takes place, and in the space surrounding the combustion zone simultaneously reacting steam with the highly heated surplus fuel which is not burned with oxygen.

6. The method of producing gas of high calorific value from both liquid and solid fuels simultaneously which comprises maintaining a zone of combustion into which no steam is allowed to enter by axially impinging a stream of oxygen and of solid fuel transported therein against a stream of liquid fuel, the ratio of the masses of fuel and oxygen being greater than that required for the oxidation that occurs, and simultaneously contacting steam with the highly heated products and with the heated surplus fuel not burned with oxygen in a region surrounding the impinging streams.

CLAUDE C. VAN NUYS. 

